Ascorbic acid content of fruit juice Essay

OBJECTIVETo determine ascorbic paneling center in a standard of produce succus by victimisation titration method with 0.001M 2,6-dichlorophenolindophenol, C12H7O2NCl2.INTRODUCTIONimage00.pngStructure of Ascorbic acerbicAscorbic dit, the chemical term for vitamin C, argon demonst array naturally in ingatherings and green vegetables. It is a dietary requirement for normal metabolism, make-up of collagen, wound healing, and tissue repair. Ascorbic sulfurous is oft quantify used as an antioxidant to help frustrate free radical damage in the skin, builds resistance to infection, aids in the taproom treatment of the common cold, and aids in the absorption of iron.Yet, vitamin C lowlife non be synthesized by the personate, and needs to be ingested. A miss of vitamin C can cause abnormalities of the spine, scurvy, and a reduction in the ability of the body to heal wounds.The determining factors as to whether fundamental fertilizer substances can be decided in an aqueous m edium depend generally on the functional groups that characterise the oxidisation-reduction properties. The determination of ascorbic caustic issue is ground on the oxidisation of ascorbic sulfurous to dehydroascorbic battery- loony toons C6H8O6 C6H6O6 + 2e- + 2H+image01.pngThe redox potential depends on the pH and without adequate buffering the pH at the electrode ascend can be displaced by the oxidization re live up to of the ascorbic venomous leading to poster broadening.Vitamin C is found in consume drinks such as orange succus and overly other sources like vegetables, colorful and kidney meat. Vitamin C in food can be destroyed by cooking, take away out from takes and vegetable during washing, and being oxidise when expose to the air. Thus, food that rich in vitamin C needs to be stored and prep bed well.PROCEDURE1. Standardization of 0.001M 2, 6-dichlorophenolindophenol declaration. 25.00mL aliquot of ascorbic acid effect was pipet into a 100mL conelike flask. 0.001M 2, 6-dichlorophenolindophenol ancestor is titrated until a faint coloration persisted for at least 15 seconds.The meter of the dye solution is calculated by the result obtained.2. Ascorbic acid concentration of fruit juice is determined.5mL of fruit juice was pipette into a 100mL cone-shaped flask. 10mL of 5M acetic acid, 5mL of dimethyl ketone ( counter interference of SO2) and 30mL of water was added, then the commixture was allowed to stand for 5 minutes and titrated with 2, 6-dichlorophenolindophenol solution.3. CuSO4 and glinting to air.2 flasks is set up and make full with 25mL of fruit juice in distributively flask. 1mg of fuzz sulfate is added to one of the flasks and both(prenominal) argon put to bubbled air for 20 minutes. The titration is repeated at the completion of the 20 minutes of air bubbling.DCPIP is a chemical compound used as a redox dye. This dye is black in base (DCPIP-) and criticize in acid (DCPIPH) and the pink form can be reduced b y ascorbic acid to a colorless form (DCPIPH2).image03.pngTitration with 0.001M 2,6- dichlorophenolindophenol solutionchemical reaction 1 DCPIP- (blue) +H+ DCPIPH (pink)Reaction 2 DCPIPH (pink) + Ascorbic acid DCPIPH2 (clear) +DehydroascorbateIf a drop of blue DCPIP dye is added to a low pH solution (pH<4.0), it allow for turn pink (Reaction 1). If a suitable electron contributeer such as ascorbic acid is present in that solution, it testament turn colorless (Reaction 2). When all of the ascorbic acid in the solution has been oxidized to dehydroascorbate, no more electrons allow for be avai testing groundle to reduce a drop of DCPIPH to the colorless form and the solution will remain pink (Reaction 2 will non take place). The end- visor was a faint pink colour that persisted for 15 seconds.(http//www.bbc.co.uk/schools/ks3bitesize/sosteacher/science/45432.shtml)Acetic acid added in Step 2 (iii) and Step 4 of the method will reduce the oxidisation of the ascorbic acid by hu mble the pH of the orange juice to retard the action of the enzyme polyphenol oxidase. If the pH is reduced below 3.0, the polyphenol oxidase will be inactivated. Acetic acid also reduces interference from any iron present, and thereby facilitates subsequent clarification of the extract. Since the ascorbic acid is not oxidized, it was existed in L-enantiomer form. Therefore, the L-enantiomer form of ascorbic acid was determined in this experiment.( James , 1999 )(http//ag.udel.edu/other_websites/foodworkshop/WSFWorkshop/Enzymatic%20Browning%20(Ch2).htm)image04.pngFrom the experiment, the metre of the ascorbic acid and the dye solution computed are 0.001134 counterspy/L and 9.8425 10-4 mol/L respectively. Hence, the concentration of the ascorbic acid in the fruit juice is 3.27mg/100ml which is very much more lower compared to the amount stated in the fruit label (Sunkist) in which the ascorbic acid content is 150mg/100ml. The high discrepancy between these ii values mogul be a scribable to the oxidization of ascorbic acid, which was exposed to the oxygen for a period of clock due to the deficient of apparatus in the laboratory. This can be improved by not exposing ascorbic acid to oxygen, coats, light and heat, as it can be oxidized easily. Therefore, it must be stored in dark and cold and but not in a admixture containment.The mechanisms of ascorbic acids degradation is comm totally due to the effect of metal ions and the presence or absence of oxygen. The rate of oxidative degradation of ascorbic acids is commonly proportional to the concentration of ascorbate monoanion (HA-), molecular oxygen and the metal ion. It is known that uncatalyzed oxidation is essentially paltry but the presence of trace metals in food are responsible for some of the oxidative degradations. The potency of metal ions in catalyzing ascorbate degradation depends on the metal involved, its oxidation state, and the presence of cheletors. For ex adenosine monophosphatele, Cu (II) is just about 80 times more potent than Fe(III) while te chelate of Fe(II) and ethylenediaminetetraacetic acid (ETDA) complex is about 4 times more catalytic than free Fe(III). (Fennema , 1996)In this experiment, the potency of copper (II) sulfate in catalyzing ascorbate degradation was tested. whiz of the conical flask with only fruit juice act as control. It is titrated with 44.70ml of DCPIP for oxidation to occur. On the other hand, another conical flask with fruit juice and 1 mg of copper sulfate titrated with only 11.70ml of DCPIP for oxidation to occur. It is proven that the presence of metal ions responsible for accelerates the rate of degradation of ascorbic acid in an air-saturated fruit juice as less DCPIP is needed. During the step 5, bubbling finished air is apply to the ascorbic acid to sharpen the oxidation of ascorbic acid by the catalyst, copper. If not, it will consume a trade of time before the reaction can take place.Advantages2,6-Dichlorophenolindophen ol served as a good electron acceptor.DCPIP is used as the titrant because it only oxidises ascorbic acid and not other substances that might be present and it acts as a self-indicator in the titrationIt is reasonably accurate, rapid, and convenient.Can be applied to many different types of experiments.DisadvantagesThe end point of a titration for this reaction is difficult to experience due to the lack of complete decolourisation of the DCPIP.These methods are not specific or are not very sensitive.The reagent itself is not invariable and needs standardization before use.If the sample solution is intensely coloured (fruit juice or syrup), end point contracting will be difficult.Better pickaxe for vitamin CAccording to the hypothesis, content of vitamin C in fresh fruit is compute to be higher than commercial piece of ground fruit juice. Due to a lot of processing, most of the vitamin C in commercial fruit juice are destroy.The few amounts of millilitres of juice it took to turn DCPIP from blue to clear, the big the amount of vitamin C there was in the drink. Many of the commercial fruit juice are heavily fortified with vitamin C. closing curtainThe molarity of the ascorbic acid and the dye solution computed are 0.001134 mol/L and 9.8425 10-4 mol/L respectively. The concentration of the ascorbic acid in the fruit juice is3.27 mg/100mL which is much more lower than the ascorbic acid content of the label product (15 mg/100mL). this might be due to the oxidation of ascorbic acid.Ascorbic acid (vitamin C) is essential to humans. It is involved in the subtraction of collagen, which is the main constituent of skin, connective tissue, and the organic substance of bones and teeth. A insufficiency of vitamin C results in a disorder called scurvy. A quantity of 60 mg vitamin C per day is enough to prevent the disease, and this is the recommended daily dietary allowance (RDA).(http//a-s.clayton.edu/ptodebus/CHEM1211/lab/experiments/Vitamin%20C/Vit%20C%20titra tion%20v1.doc)REFERENCESCeirwyn S.James , 1999, Analytical Chemistry of feeds , An Aspen Publications , page 138,139Owen R. Fennema, 1996, Food Chemistry, Third Ed., Marcel Deeker,Inc., pg 561,562http//www.bbc.co.uk/schools/ks3bitesize/sosteacher/science/45432.shtmlhttp//www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd= bring forward&db=PubMed&list_uids=7016874&dopt=Abstracthttp//darwin.nmsu.edu/blyons/BCHE_397/VitaminC.htmhttp//www-saps.plantsci.cam.ac.uk/docs/vitc.pdfhttp//journals.tubitak.gov.tr/chem/issues/kim-02-26-5/kim-26-5-8-0106-6.pdfsearch=Determination%20of%20ascorbic%20acid%20by%20DCPIP entryhttp//www.naturalhub.com/natural_food_guide_fruit_vitamin_c.htmhttp//ag.udel.edu/other_websites/foodworkshop/WSFWorkshop/Enzymatic%20Browning%20(Ch2).htmhttp//a-s.clayton.edu/ptodebus/CHEM1211/lab/experiments/Vitamin%20C/Vit%20C%20titration%20v1.doc